When drilling stainless, even 303, you have to use slow RPM and strong feed on the drill, along with lots of oil. If not you will "glaze", or work harden, the surface. A real pain. You then have to switch to carbide to get through the hard spot. If you let off on drill pressure abit you will do the same! Once you start to cut, DON'T STOP!!.
Drilling the blank...
With the blank now drilled I'll start to knurl the "lock" feature. I don't hollow the cup area yet because of the side pressure used in knurling. You would deform the piece!
Here are some straight knurling tools...
Diamond knurls are just helical shaped wheels one under and one over that mesh to make the diamond shape, like on tele knobs. For the cup I used a straight knurl.
You slowley "press" the shape of the tool into the metal...
I didn't take much care in doing this since it won't be seen, but you get the idea.
Once the knurl is finished I cut the piece off and turn it and place it in a 7/8 collet to bore the cup area...
When the cup area is done I polish it and remove it to put on a fixture to finish the back of the cup.